Autonomous docking of spacecraft using the Cognachrome Vision
System

The University
of Maryland Space Systems Laboratory and the KISS
Institute for Practical Robotics (with cooperation from Newton Research Labs) have simulated
autonomous spacecraft docking in a neutral buoyancy tank for inclusion
on the UMDs Ranger space vehicle. Using a composite target
of three brightly-colored objects designed by David
P. Miller, the spacecraft knows its distance and orientation,
and can servo to arbitrary positions around the target.

Determining your position from a composite target

David P. Miller and Anne Wright. Autonomous
Spacecraft Docking Using Multi-Color Targets. In Proceedings
of the 6th Topical Meeting on Robotics, Monterey, CA, February
1995.

The target is composed of three parts: "L",
"C", and "R" (left, center, and right). "X"
is the position of the camera. Note that q is measured in the plane
of LRX, not LRC.

Relationships yielding the 3-dimensional
position of the robot relative to the target, given the 2-dimensional
positions (in camera space) of the three target elements as viewed
from the robot. xl, yl, xc,
yc, xr, yr are the positions,
in camera space, of the left, center, and right targets, respectively,
as viewed from the robot.